It is proposed to evaluate the urethane polymers for use as maxillofacial prostheses. These materials are readily available and have physical properties compatible for use as extraoral prostheses. Published data on the polyurethane systems indicate that these materials can be adapted to use for maxillofacial prostheses more easily and simply than the presently used materials. The main difficulty with most commercially available urethane systems is the possible toxicity of the aromatic isocyanate (toluene diisocyanate). We propose to survey the existing urethane systems, as well as the one presently available (Dermathane), testing for hardness, modulus, tensile strength, elongation, tear resistance, and the durability or weatherability of each. Computer processing of data derived by sequential variation of formulation parameters will allow us to examine the interrelationships between properties and can assist in determining if a compromise can be made in the superior properties to improve the deficient ones to achieve a better balance. This screening and optimization will narrow the field to a few promising materials, which will be further evaluated and tested for toxicity. The successful materials will be prepared for clinical use and tested in the Maxillofacial Center. Careful records of patient habits, environment, and use will be mainained to grade and evaluate any deterioration. Feedback from clinic to the testing laboratory to the compounding chemist will be used to further improve the materials. Refinements of this process will result in one or more materials that will have better properties, better availability, be more easily used, and be less expensive than any materials now in use.